Conventionally, figures and the like that create an optical illusion have been discovered. For example, illusion figures, such as a Hermann grid, a Chevreul illusion, a Cafe Wall illusion, an Ouchi illusion, a Pinna illusion, and a Gurnsey-Morgan illusion, have been discovered, and an illusion phenomenon is induced by viewing these illusion figures, illusions such as the size, position, color, or the like being perceived differently from reality, a non-existent object being seen, and a still image appearing to move (see Non Patent Literature 1, 4, 5, 6, and 7).
Moreover, conventionally, wavelet frames with orientation selectivity referred to as a pinwheel wavelet frame (see Non Patent Literature 3), a simple pinwheel framelet (see Non Patent Literature 2), and a pinwheel framelet have been developed as mathematical models of simple cells in the human visual cortex, and are used for image analysis and the like.